Surgical Instrument

ABSTRACT

A surgical instrument comprising a handle assembly, a body, a tool assembly and an articulation assembly is disclosed. The articulation mechanism includes a receptacle, and a main shaft. A lower clutch is fixedly positioned within the receptacle and has a serrated portion including a plurality of serrations. An upper clutch includes at least one projection positioned to engage the serrations of the lower clutch to releasably retain the main shaft at a rotatably fixed position. An angle between a first pair of adjacent serrations is defined as a first angle, an angle between a second pair of adjacent serrations is defined as a second angle, and an angle between a third pair of adjacent serrations is defined as a third angle. The first angle, the second angle, and the third angle are each different from one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/200,004, filed Aug. 28, 2008 and also claims benefit of U.S.Provisional Application No. 60/967,169, filed Aug. 31, 2007, thedisclosures of which are hereby incorporated by reference herein.

BACKGROUND

1. Technical Field

This application relates to a surgical instrument, and moreparticularly, to an articulating mechanism for use with an endoscopicsurgical instrument.

2. Background of Related Art

Surgical devices wherein tissue is first grasped or clamped betweenopposing jaw structure and then joined by surgical fasteners are wellknown in the art. In some instruments a knife is provided to cut thetissue which has been joined by the fasteners. The fasteners aretypically in the form of surgical staples but two part polymericfasteners can also be utilized.

Instruments for this purpose can include two elongated members which arerespectively used to capture or clamp tissue. Typically, one of themembers carries a staple cartridge which houses a plurality of staplesarranged in at least two lateral rows while the other member has ananvil that defines a surface for forming the staple legs as the staplesare driven from the staple cartridge. Generally, the stapling operationis effected by cam bars that travel longitudinally through the staplecartridge, with the cam bars acting upon staple pushers to sequentiallyeject the staples from the staple cartridge. A knife can travel betweenthe staple rows to longitudinally cut and/or open the stapled tissuebetween the rows of staples. Such instruments are disclosed, forexample, in U.S. Pat. No. 3,079,606 and U.S. Pat. No. 3,490,675.

A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a doublerow of staples on each side of the incision. This is accomplished byproviding a disposable loading unit in which a cam member moves throughan elongate guide path between two sets of staggered staple carryinggrooves. Staple drive members are located within the grooves and arepositioned in such a manner so as to be contacted by the longitudinallymoving cam member to effect ejection of the staples from the staplecartridge of the disposable loading unit. Other examples of suchstaplers are disclosed in U.S. Pat. Nos. 4,429,695 and 5,065,929.

Each of the instruments described above were designed for use inconventional surgical procedures wherein surgeons have direct manualaccess to the operative site. However, in endoscopic or laparoscopicprocedures, surgery is performed through a small incision or through anarrow cannula inserted through small entrance wounds in the skin. Inorder to address the specific needs of endoscopic and/or laparoscopicsurgical procedures, endoscopic surgical stapling devices have beendeveloped and are disclosed in, for example, U.S. Pat. Nos. 5,040,715(Green, et al.); 5,307,976 (Olson, et al.); 5,312,023 (Green, et al.);5,318,221 (Green, et al.); 5,326,013 (Green, et al.); and 5,332,142(Robinson, et al.).

U.S. Surgical, the assignee of the present application, has manufacturedand marketed endoscopic stapling instruments, such as the Multifire ENDOGIA* 30 instrument, for several years. These instruments have providedsignificant clinical benefits. Nonetheless, improvements are possible,for example, by reducing the cost and complexity of manufacture.

Current laparoscopic linear stapling devices are configured to operatewith disposable loading units and/or staple cartridges of only one size.For example, individual linear staplers are presently available forapplying parallel rows of staples measuring 30 mm, 45 mm and 60 mm inlength. Thus, during a normal operation, a surgeon may be required toutilize several different stapling instruments to perform a singlelaparoscopic surgical procedure. Such practices increase the time,complexity and overall costs associated with laparoscopic surgicalprocedures. In addition, costs are greater in designing andmanufacturing multiple stapler sizes, as opposed to creating a single,multipurpose stapler.

SUMMARY

The present disclosure relates to a surgical instrument comprising ahandle assembly, a body, a tool assembly and an articulation assembly.The body extends distally from the handle assembly and defining a firstlongitudinal axis. The tool assembly is pivotably supported on a distalend of the body and defines a second longitudinal axis. The toolassembly is pivotable between a non-articulated position in which thefirst longitudinal axis is aligned with the second longitudinal axis andat least one articulated position in which the second longitudinal axisis at an angle to the first longitudinal axis. The articulationmechanism includes a receptacle positioned adjacent the handle assembly,and a main shaft having a base portion. The main shaft is rotatablysupported within the receptacle. A lower clutch is fixedly positionedwithin the receptacle and has a serrated portion including a pluralityof serrations and being positioned about the main shaft. An upper clutchis slidably positioned about the main shaft and is rotatably fixed tothe main shaft such that rotation of the main shaft affects rotation ofthe upper clutch. The upper clutch includes at least one projectionpositioned to engage the serrations of the lower clutch to releasablyretain the main shaft at a rotatably fixed position. The articulationlink has a proximal end operatively connected to the base portion of themain shaft and a distal end operatively connected to the tool assembly.The main shaft is rotatable to move the articulation link to affectmovement of the tool assembly between the non-articulated position andthe at least one articulated position. An angle between a first pair ofadjacent serrations is defined as a first angle, an angle between asecond pair of adjacent serrations is defined as a second angle, and anangle between a third pair of adjacent serrations is defined as a thirdangle. The first angle, the second angle, and the third angle are eachdifferent from one another.

The present disclosure also relates to an articulation mechanism foraffecting movement of a tool assembly of a surgical instrument between anon-articulated position and at least one articulated position. Thearticulation mechanism comprises a receptacle, a main shaft, a lowerclutch and an upper clutch. The main shaft has a base portion and isrotatably supported within the receptacle. The lower clutch is fixedlypositioned within the receptacle and has a serrated portion including aplurality of serrations and being positioned about the main shaft. Theupper clutch is slidably positioned about the main shaft and isrotatably fixed to the main shaft such that rotation of the main shaftaffects rotation of the upper clutch. The upper clutch includes at leastone projection positioned to engage the serrations of the lower clutchto releasably retain the main shaft at a rotatably fixed position. Anangle between a first pair of adjacent serrations is defined as a firstangle, an angle between a second pair of adjacent serrations is definedas a second angle, and an angle between a third pair of adjacentserrations is defined as a third angle. Each of the first angle, thesecond angle, and the third angle are different from one another.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are described herein with reference to the drawings:

FIG. 1 is a perspective view of one preferred embodiment of thepresently disclosed surgical instrument;

FIG. 2 is a top view of the surgical instrument shown in FIG. 1;

FIG. 3 is a side view of the surgical instrument shown in FIG. 1;

FIG. 4 is a perspective view with parts separated of the handle assemblyof the surgical instrument shown in FIG. 1;

FIG. 5 is a cross-sectional view of a portion of the firing lockoutmechanism shown in FIG. 4;

FIG. 6 is a perspective of the slide plate of the anti-reverse clutchmechanism of the surgical instrument;

FIG. 7 is an enlarged perspective view of the anti- reverse clutchmechanism shown in FIG. 1;

FIG. 8 is a side cross-sectional view of the surgical instrument shownin FIG. 1 in the non-actuated position with the disposable loading unitremoved;

FIG. 9 is a perspective view with parts separated of the rotationmember, the articulation mechanism, and the elongated body of thesurgical instrument shown in FIG. 1;

FIG. 10 is an enlarged view of the indicated area of detail shown inFIG. 8;

FIG. 10 a is a perspective view of the translation member of thearticulating mechanism and the proximal end of the elongated body of thesurgical instrument shown in FIG. 1;

FIG. 10 b is an enlarged cross-sectional view of the indicated area ofdetail of FIG. 8;

FIG. 10 c is a cross-sectional view along section line 10 c-10 c of FIG.8;

FIG. 11 is a perspective view of the cam member of the articulationmechanism of the surgical instrument shown in FIG. 1;

FIG. 12 is a top view of the cam member of the articulation mechanism ofthe surgical instrument shown in FIG. 1;

FIG. 12 a is a perspective view of a non-articulating disposable loadingunit usable with the surgical instrument shown in FIG. 1;

FIG. 12 b is a perspective view of the preferred articulating disposableloading unit of the surgical instrument shown in FIG. 1;

FIG. 13 is a cross-sectional view taken along section line 13-13 of FIG.10;

FIG. 14 is a cross-sectional view taken along section line 14-14 of FIG.10;

FIG. 15 is a cross-sectional view taken along section line 15-15 of FIG.10;

FIG. 16 is an enlarged view of the indicated area of detail shown inFIG. 8;

FIG. 17 is a side perspective view of the blocking plate of the surgicalinstrument shown in FIG. 1;

FIG. 18 is a top perspective view of the blocking plate of the surgicalinstrument shown in FIG. 1;

FIG. 19 is a perspective view of a disposable loading unit usable withthe surgical instrument of FIG. 1;

FIG. 20 is another perspective view of a disposable loading unit usablewith the surgical instrument of FIG. 1;

FIG. 21 is a perspective view of the tool assembly of the surgicalinstrument of FIG. 1 with parts separated;

FIG. 22 is an enlarged perspective view of the distal end of the anvilassembly showing a plurality of staple deforming cavities;

FIG. 23 is an enlarged perspective view of the distal end of the staplecartridge of the surgical instrument shown in FIG. 1;

FIG. 24 is a side cross-sectional view taken along section line 24-24 ofFIG. 23;

FIG. 25 is a bottom perspective view of the staple cartridge shown inFIG. 21;

FIG. 26 is an enlarged perspective view of the actuation sled, thepushers and the fasteners shown in FIG. 21;

FIG. 27 is an enlarged perspective view with parts separated of theproximal housing portion and mounting assembly of the disposable loadingunit shown in FIG. 19;

FIG. 28 is an enlarged perspective view of the mounting assembly of thedisposable loading unit shown in FIG. 19 mounted to a distal end portionof the proximal housing portion;

FIG. 29 is an enlarged perspective view of the proximal housing portionand the mounting assembly of the disposable loading unit shown in FIG.19 with the upper housing half removed;

FIG. 30 is a perspective view of the proximal housing portion and themounting assembly of the disposable loading unit shown in FIG. 19 withthe upper housing half removed;

FIG. 31 is a perspective view with parts separated of the axial driveassembly;

FIG. 32 is an enlarged perspective view of the axial drive assemblyshown in FIG. 31;

FIG. 33 is an enlarged perspective view of the proximal end of the axialdrive assembly shown in FIG. 31 including the locking device;

FIG. 34 is an enlarged perspective view of the distal end of the axialdrive assembly shown in FIG. 31;

FIG. 35 is an enlarged perspective view of the distal end of theelongated body of the stapling apparatus shown in FIG. 1;

FIG. 36 is an enlarged perspective view of the locking device shown inFIG. 33;

FIG. 37 is an enlarged perspective view of a lower housing half of theproximal housing portion of the disposable loading unit shown in FIG.27;

FIG. 38 is a side cross-sectional view of the disposable loading unitshown in FIG. 20;

FIG. 39 is an enlarged view of the indicated area of detail shown inFIG. 38;

FIG. 40 is a perspective view of the surgical instrument shown in FIG. 1with the disposable loading unit of FIG. 19 detached from the elongatedbody;

FIG. 41 is an enlarged perspective view of the disposable loading unitof FIG. 19 during attachment to the elongated body of the surgicalinstrument shown in FIG. 1;

FIG. 42 is another enlarged perspective view of the disposable loadingunit of FIG. 19 during attachment to the elongated body of the surgicalinstrument shown in FIG. 1;

FIG. 43 is a cross-sectional view taken along section line 43-43 of FIG.41;

FIG. 43 a is a side cross-sectional view of the rotation knob,articulation mechanism, and sensing mechanism during insertion of adisposable loading unit into the elongated body of the surgicalinstrument;

FIG. 44 is a cross-sectional view taken along section line 44-44 of FIG.42;

FIG. 45 is a side cross-sectional view of the distal end of thedisposable loading unit of FIG. 1 with tissue positioned between theanvil and clamp assemblies;

FIG. 46 is a side cross-sectional view of the handle assembly with themovable handle in an actuated position;

FIG. 47 is an enlarged view of the indicated area of detail shown inFIG. 46;

FIG. 48 is a cross-sectional view of the proximal end of the disposableloading unit of FIG. 19 and the distal end of the elongated body of thesurgical instrument shown in FIG. 1 with the control rod in a partiallyadvanced position;

FIG. 49 is a cross-sectional view of the tool assembly of the surgicalinstrument shown in FIG. 1 positioned about tissue in the clampedposition;

FIG. 50 is a cross-sectional view of the handle assembly of the staplingapparatus of FIG. 1 during the clamping stroke of the apparatus;

FIG. 51 is a side cross-sectional view of the distal end of the toolassembly of the stapling apparatus shown in FIG. 1 during firing of theapparatus;

FIG. 52 is a side cross-sectional view of the distal end of the toolassembly of the stapling apparatus shown in FIG. 1 after firing of theapparatus;

FIG. 53 is a side cross-sectional view of the handle assembly of theapparatus during retraction of the actuation shaft;

FIG. 54 is a side cross-sectional view of the handle assembly of thestapling apparatus during actuation of the emergency release button;

FIG. 55 is a top view of the articulation mechanism of the surgicalinstrument;

FIG. 56 is a side cross-sectional view of the articulation mechanism androtation member of the surgical instrument shown in FIG. 1;

FIG. 57 is a top view of the distal end of the elongated body, themounting assembly, and the proximal end of the tool assembly duringarticulation of the stapling apparatus;

FIG. 58 is a perspective view of the surgical instrument duringarticulation of the tool assembly;

FIG. 59 is a perspective view of the surgical instrument duringarticulation and rotation of the tool assembly;

FIG. 60 is a top view of the distal end of the disposable loading unitimmediately prior to articulation;

FIG. 61 is a top view of the distal end of the elongated body, themounting assembly, and the proximal end of the tool assembly duringarticulation of the stapling apparatus;

FIG. 62 is a partial cross-sectional view of a portion of the disposableloading unit during retraction of the locking device; and

FIG. 63 is a partial cross-sectional view of a portion of the disposableloading unit with the locking device in the locked position.

FIG. 64 is a perspective view of another embodiment of the presentlydisclosed articulation mechanism;

FIG. 65 is a perspective view of the articulation mechanism shown inFIG. 64 with parts separated;

FIG. 66 is a perspective view of the rotatable member of thearticulation mechanism shown in FIG. 64 with the lower clutch positionedin the receptacle of the rotatable member;

FIG. 67 is a bottom view of the cam member, main shaft and translationmember of the articulation mechanism shown in FIG. 65;

FIG. 68 is a bottom side perspective view of the upper clutch of thearticulation mechanism shown in FIG. 65;

FIG. 68A is a perspective view of a lower face of an upper clutchaccording to an alternate embodiment of the present disclosure;

FIG. 69 is a perspective view from the top of the upper clutch shown inFIG. 68;

FIG. 70 is a top perspective view of the lower clutch of thearticulation mechanism shown in FIG. 65;

FIG. 70A is a top perspective view of a lower clutch according to analternate embodiment of the present disclosure;

FIG. 71 is a top perspective view of the main shaft of the articulationmechanism shown in FIG. 65;

FIG. 72 is a bottom perspective view of the main shaft shown in FIG. 71;

FIG. 73 is a top perspective view of the cover of the articulationmechanism shown in FIG. 65;

FIG. 74 is a bottom perspective view of the cover shown in FIG. 73;

FIG. 75 is a cross-sectional view of the articulation mechanism shown inFIG. 64 with the articulation mechanism in a non-articulated position;

FIG. 76 is a cross-sectional view taken along section lines 76-76 ofFIG. 75;

FIG. 77 is a top view of the articulation mechanism shown in FIG. 64with the articulation lever rotated;

FIG. 78 is a cross-sectional view of the articulation mechanism shown inFIG. 64 with the articulation lever rotated as shown in FIG. 77;

FIG. 79 is a cross-sectional view taken along section lines 79-79 ofFIG. 78; and

FIG. 80 is a cross-sectional view of the articulation mechanism shown inFIG. 64 with the articulation lever rotated and the upper clutchprojection reengaged with the serrations of the lower clutch.

DETAILED DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the presently disclosed endoscopic surgicalinstrument will now be described in detail with reference to thedrawings, in which like reference numerals designate identical orcorresponding elements in each of the several views.

In the drawings and in the description that follows, the term“proximal”, as is traditional, will refer to the end of the staplingapparatus which is closest to the operator, while the term distal willrefer to the end of the apparatus which is furthest from the operator.

FIGS. 1-3 illustrate one embodiment of the presently disclosed surgicalinstrument shown generally as 10. Briefly, surgical instrument 10includes a handle assembly 12 and an elongated body 14. A disposableloading unit or DLU 16 is releasably secured to a distal end ofelongated body 14. Disposable loading unit 16 includes a tool assembly17 having a cartridge assembly 18 housing a plurality of surgicalstaples and an anvil assembly 20 movably secured in relation tocartridge assembly 18. Disposable loading unit 16 is configured to applylinear rows of staples measuring from about 30 mm to about 60 mm inlength. Disposable loading units having linear rows of staples of otherlengths are also envisioned, e.g., 45 mm. Handle assembly 12 includes astationary handle member 22, a movable handle member 24, and a barrelportion 26. A rotatable member 28 is preferably mounted on the forwardend of barrel portion 26 to facilitate rotation of elongated body 14with respect to handle assembly 12. An articulation lever 30 is alsopreferably mounted on the forward end of barrel portion 26 adjacentrotatable knob 28 to facilitate articulation of tool assembly 17. A pairof retraction knobs 32 are movably positioned along barrel portion 26 toreturn surgical instrument 10 to a retracted position, as will bedescribed in detail below.

Referring to FIG. 4, handle assembly 12 includes housing 36, which ispreferably formed from molded housing half-sections 36 a and 36 b, whichforms stationary handle member 22 and barrel portion 26 of handleassembly 12 (See FIG. 1). Movable handle member 24 is pivotablysupported between housing half-sections 36 a and 36 b about pivot pin38. A biasing member 40, which is preferably a torsion spring, biasesmovable handle 24 away from stationary handle 22. An actuation shaft 46is supported within barrel portion 26 of housing 36 and includes atoothed rack 48. A driving pawl 42 having a rack engagement finger 43with laterally extending wings 43 a and 43 b is pivotably mounted to oneend of movable handle 24 about a pivot pin 44. A biasing member 50,which is also preferably a torsion spring, is positioned to urgeengagement finger 43 of driving pawl 42 towards toothed rack 48 ofactuation shaft 46. Movable handle 24 is pivotable to move engagementfinger 43 of driving pawl 42 into contact with toothed rack 48 ofactuation shaft 46 to advance the actuation shaft linearly in the distaldirection. The forward end of actuation shaft 46 rotatably receives theproximal end 49 of a control rod 52 such that linear advancement ofactuation shaft 46 causes corresponding linear advancement of controlrod 52. A locking pawl 54 having a rack engagement member 55 ispivotably mounted within housing 36 about pivot pin 57 and is biasedtowards toothed rack 48 by biasing member 56, which is also preferably atorsion spring. Engagement member 55 of locking pawl 54 is movable intoengagement with toothed rack 48 to retain actuation shaft 46 in alongitudinally fixed position.

A retraction mechanism 58 which includes a pair of retractor knobs 32(See FIG. 1) is connected to the proximal end of actuation shaft 46 by acoupling rod 60. Coupling rod 60 includes right and left engagementportions 62 a and 62 b for receiving retractor knobs 32 and a centralportion 62 c which is dimensioned and configured to translate within apair of longitudinal slots 34 a formed in actuation shaft 46 adjacentthe proximal end thereof. A release plate 64 is operatively associatedwith actuation shaft 46 and is mounted for movement with respect theretoin response to manipulation of retractor knobs 32. A pair of spacedapart pins 66 extend outwardly from a lateral face of actuation shaft 46to engage a pair of corresponding angled cam slots 68 formed in releaseplate 64. Upon rearward movement of retractor knobs 32, pins 66 canrelease plate 64 downwardly with respect to actuation shaft 46 and withrespect to toothed rack 48 such that the bottom portion of release plate64 extends below toothed rack 48 to disengage engagement finger 43 ofdriving pawl 42 from toothed rack 48. A transverse slot 70 is formed atthe proximal end of release plate 64 to accommodate the central portion62 c of coupling rod 60, and elongated slots 34 (See FIG. 1) are definedin the barrel section 26 of handle assembly 12 to accommodate thelongitudinal translation of coupling rod 60 as retraction knobs 32 arepulled rearwardly to retract actuation shaft 46 and thus retract controlrod 52 rearwardly. Actuation shaft 46 is biased proximally by spring 72which is secured at one end to coupling rod portion 62 via connector 74and at the other end to post 76 on actuation shaft 46.

Referring also to FIG. 5, handle assembly 12 includes a firing lockoutassembly 80 which includes a plunger 82 and a pivotable locking member83. Plunger 82 is biased to a central position by biasing springs 84 andincludes annular tapered camming surfaces 85. Each end of plunger 82extends through housing 36 (See FIG. 1) adjacent an upper end ofstationary handle 22. Pivotable locking member 83 is pivotably attachedat its distal end between housing half-sections 36 a and 36 b aboutpivot pin 86 and includes a locking surface 88 and proximal extension 90having a slot 89 formed therein. Locking member 83 is biased by spring92 counter-clockwise (as viewed in FIG. 4) to move locking surface 88 toa position to abut the distal end of actuation shaft 46 to preventadvancement of shaft 46 and subsequent firing of stapling apparatus 10Annular tapered camming surface 85 is positioned to extend into taperedslot 89 in proximal extension 90. Lateral movement of plunger 82 ineither direction against the bias of either spring 84 moves taperedcamming surface 85 into engagement with the sidewalls of tapered slot 89to pivot locking member 83 clockwise about pivot pin 86, as viewed inFIG. 4, to move blocking surface 88 to a position to permit advancementof actuation shaft 46 and thus firing of stapling apparatus 10. Blockingsurface 88 is retained in this position by recesses 87 which receive thetapered tip of camming surface 85 to lock locking member 83 in acounter-clockwise position. Operation of firing lockout assembly 80 willbe further illustrated below.

Referring to FIGS. 4, 6, and 7, handle mechanism 12 also includes ananti-reverse clutch mechanism which includes a first gear 94 rotatablymounted on a first shaft 96, and second gear 98 mounted on a secondshaft 100, and a slide plate 102 (FIGS. 6 and 7) slidably mounted withinhousing 36. Slide plate 102 includes an elongated slot 104 dimensionedand configured to be slidably positioned about locking pawl pivot pin57, a gear plate 106 configured to mesh with the teeth of second gear98, and a cam surface 108. In the retracted position, cam surface 108 ofslide plate 102 engages locking pawl 54 to prevent locking pawl 54 fromengaging toothed rack 48. Actuation shaft 46 includes a distal set ofgear teeth 110 a spaced from a proximal set of gear teeth 110 bpositioned to engage first gear 94 of actuation shaft 46 during movementof actuation shaft 46. When actuation shaft 46 is advanced by pivotingmovable handle 24 about pivot pin 38, distal gear teeth 110 a onactuation shaft 46 mesh with and rotate first gear 94 and first shaft96. First shaft 96 is connected to second shaft 100 by spring clutchassembly such that rotation of first shaft 96 will cause correspondingrotation of second shaft 100. Rotation of second shaft 100 causescorresponding rotation of second gear 98 which is engaged with gearplate 106 on slide plate 102 to cause linear advancement of slide plate102. Linear advancement of slide plate 102 is limited to the length ofelongated slot 104. When slide plate has been advanced the length ofslot 104, cam surface 108 releases locking pawl 54 such that it is movedinto engagement with toothed rack 48. Continued advancement of actuationshaft 46 eventually moves gear teeth 110 b into engagement with gearplate 106. However, since slide plate 102 is longitudinally fixed inposition, the spring clutch is forced to release, such that continueddistal advancement of actuation shaft 46 is permitted.

When actuation shaft 46 is returned to the retracted position (bypulling retraction knobs 34 proximally, as discussed above) gear teeth110 b engage first gear 94 to rotate second gear 98 in the reversedirection to retract slide member 102 proximally within housing 36.Proximal movement of slide member 102 advances cam surface 108 intolocking pawl 54 prior to engagement between locking pawl 54 and toothedrack 48 to urge locking pawl 54 to a position to permit retraction ofactuation shaft 46.

Referring again to FIG. 4, handle assembly 12 includes an emergencyreturn button 112 pivotally mounted within housing 36 about a pivotmember 114 supported between housing half-sections 36 a and 36 b. Returnbutton 112 includes an externally positioned member 116 positioned onthe proximal end of barrel portion 26. Member 116 is movable about pivotmember 114 into engagement with the proximal end of locking pawl 54 tourge rack engagement member 55 out of engagement with toothed rack 48 topermit retraction of actuation shaft 46 during the firing stroke of thestapling apparatus 10. As discussed above, during the clamping portionof advancement of actuation shaft 46, slide plate 102 disengages pawl 54from rack 48 and thus actuation of return button 112 is not necessary toretract the actuation shaft 46.

FIG. 8 illustrates the interconnection of elongated body 14 and handleassembly 12. Referring to FIGS. 8-10, housing 36 includes an annularchannel 117 configured to receive an annular rib 118 formed on theproximal end of rotation member 28, which is preferably formed frommolded half-sections 28 a and 28 b Annular channel 117 and rib 118permit relative rotation between rotation member 28 and housing 36.Elongated body 14 includes inner housing 122 and an outer casing 124.Inner housing 122 is dimensioned to be received within outer casing 124and includes an internal bore 126 (FIG. 8) which extends therethroughand is dimensioned to slidably receive a first articulation link 123 andcontrol rod 52. The proximal end of housing 122 and casing 124 eachinclude a pair of diametrically opposed openings 130 and 128,respectively, which are dimensioned to receive radial projections 132formed on the distal end of rotation member 28. Projections 132 andopenings 128 and 130 fixedly secure rotation member 28 and elongatedbody 14 in relation to each other, both longitudinally and rotatably.Rotation of rotation knob 28 with respect to handle assembly 12 thusresults in corresponding rotation of elongated body 14 with respect tohandle assembly 12.

An articulation mechanism 120 is supported on rotatable member 28 andincludes articulation lever 30, a cam member 136, a translation member138, and first articulation link 123 (FIG. 9). Articulation lever 30 ispivotably mounted about pivot member 140 which extends outwardly fromrotation member 28 and is preferably formed integrally therewith. Aprojection 142 extends downwardly from articulation lever 30 forengagement with cam member 136.

Referring temporarily to FIGS. 11 and 12, cam member 136 includes ahousing 144 having an elongated slot 146 extending through one sidethereof and a stepped camming surface 148 formed in the other sidethereof. Each step of camming surface 148 corresponds to a particulardegree of articulation of stapling apparatus 10. Although five steps areillustrated, fewer or more steps may be provided. Elongated slot 146 isconfigured to receive projection 142 formed on articulation lever 30.Housing 144 includes a distal stepped portion 150 and a proximal steppedportion 152. Proximal stepped portion 152 includes a recess 154.

Referring again to FIGS. 8-10 and also to FIGS. 13-15, translationmember 138 includes a plurality of ridges 156 which are configured to beslidably received within grooves 158 formed along the inner walls ofrotation member 28. Engagement between ridges 156 and grooves 158prevent relative rotation of rotation member 28 and translation member138 while permitting relative linear movement. The distal end oftranslation member 138 includes arm 160 which includes an opening 162configured to receive a finger 164 extending from the proximal end ofarticulation link 123 (See FIG. 10 a). A pin 166 having a housing 168constructed from a non-abrasive material, e.g., teflon, is secured totranslation member 138 and dimensioned to be received within steppedcamming surface 148.

In an assembled condition, proximal and distal stepped portions 150 and152 of cam member 136 are positioned beneath flanges 170 and 172 formedon rotation member 28 to restrict cam member 136 to transverse movementwith respect to the longitudinal axis of stapling apparatus 10. Whenarticulation lever 30 is pivoted about pivot member 140, cam member 136is moved transversely on rotation member 28 to move stepped cammingsurface 148 transversely relative to pin 166, forcing pin 166 to moveproximally or distally along stepped cam surface 148. Since pin 166 isfixedly attached to translation member 138, translation member 138 ismoved proximally or distally to effect corresponding proximal or distalmovement of first actuation link 123.

FIGS. 64-80 illustrate another embodiment of the presently disclosedarticulation mechanism shown generally as 420. Referring to FIGS. 64 and65, articulation mechanism 420 includes an articulation lever 422, amechanism cover 424, a biasing member 426, an upper clutch 428, a lowerclutch 430, a main shaft 432, a translation member 434, and a cam member480. The entire articulation mechanism is supported in a receptacle 436formed in the top half-section 438 a of rotatable member 438 but mayalso be supported in the handle assembly. Receptacle 436 defines asubstantially cylindrical throughbore having a shoulder 436 adimensioned to receive and support lower clutch 430. Shoulder 436 aincludes one or more tabs 440.

Referring also to FIGS. 66 and 70, lower clutch 430 includes an outerrim portion 442 and an inner circular serrated portion 444. Outer rimportion 442 includes one or more cutouts 446 which are dimensioned toreceive tabs 440 on shoulder 436 a of receptacle 436. Lower clutch 430is positioned within receptacle 436 atop shoulder 436 a such that tabs440 are received within cutouts 446 and lower clutch 430 is preventedfrom rotating within receptacle 436 (FIG. 66). Circular serrated portion444 includes a series of shallow serrations 448 and three spaced deepserrations 450 (FIG. 70). These serrations 448 and 450 include angledwalls and function to retain articulation lever 422 at a plurality ofdifferent articulated positions as will be discussed in further detailbelow. Lower clutch 430 also defines a central throughbore 430 a whichis dimensioned to receive main shaft 432.

Referring to FIGS. 65, 68 and 69, upper clutch 428 includes a hubportion 452 and a base portion 454. Hub portion 452 defines a centralthroughbore 428 a and a channel 456 which is dimensioned to receive apin 458. Pin 458 is inserted through an opening 460 in articulationlever 422 and into channel 456 to rotatably fix articulation lever 422to upper clutch 428. Hub portion 422 also includes an elongated slot 462which is dimensioned to receive a pin 464. Pin 464 is inserted throughslot 462 and a hole 466 formed in main shaft 432 to rotatably fix upperclutch 428 to main shaft 432. Pin 464 is longitudinally slidable in slot462 to allow upper clutch 428 to move axially in relation to main shaft432.

Base portion 454 of upper clutch includes an upper face 469 and a lowerface 468 (FIG. 68) which is positioned in juxtaposed alignment withserrated portion 444 of lower clutch 430. Lower face 468 includes aplurality of spaced projections 470 configured to be received withindeep and shallow serrations 450 and 448 of lower clutch 430. In oneembodiment, projections 470 have a triangularly shaped cross-section inwhich the walls defining the triangle are steeper near the apex of thetriangle. Such a configuration allows the apex of projections 470 to bereceived in shallow serrations 448 and substantially the entireprojection 470 to be received in deep serrations 450, thus effecting amore secure engagement. The shape of projections 470 has two portionsand two different engagement surfaces to define two different verticalpositions for the mechanism.

Referring to FIGS. 65, 71 and 72, main shaft 432 includes asubstantially cylindrical body portion 474 and a disc-shaped baseportion 476. Base portion 476 defines a cutout 478 (FIG. 72) andincludes a cam member or protrusion 480. Base portion 476 defines anannular support surface 482 (FIG. 71). Body portion 474 is dimensionedto extend through central throughbore 430 a of lower clutch 430 andcentral throughbore 428 a of upper clutch 428 such base portion 476 ispositioned beneath upper clutch 428 and lower clutch 430 withinreceptacle 436 of rotatable member 438. Base portion 476 also includes astepped portion 484 defining a shoulder 486. Shoulder 486 is supportedon an annular shelf 488 (FIG. 65) formed in receptacle 436 such thatmain shaft 432 is rotatably supported within receptacle 436 of rotatablemember 438.

Referring to FIGS. 65, 73 and 74, mechanism cover 424 defines an opening490 dimensioned to allow passage of hub portion 452 of upper clutch 428such that hub portion 452 can be rotatably fixed to articulation lever422. An inner cylindrical portion 492 (FIG. 74) of cover 424 includescutouts 494. When cover 424 is placed over receptacle 436 of top halfsection 438 a of rotatable member 438, cutouts 494 of cylindricalportion 492 of cover 424 receive tabs 440 and cylindrical portion 492compresses lower clutch 430 against shoulder 436 a (FIG. 65). Cover 424can be secured to rotatable member using any known fastening techniqueincluding welding, adhesives or any known mechanical attachmentstructure, e.g., screws, rivets, etc.

Referring to FIG. 65, translation member 434 includes an angled body 496which defines a cam slot 498, a cutout 500 and an arm 502 havingengagement structure 504 configured to engage a proximal end of anarticulation link 123 (FIG. 10A). Although the engagement structure 504is illustrated as a finger-like projection other mating engagementstructures are envisioned to facilitate connection of translation member434 to articulation link 123 (FIG. 10A).

Referring also to FIG. 67, cam slot 498 of translation member 434 isdimensioned to slidably receive cam member 480 of main shaft 432. Asdiscussed above, articulation lever 422 is rotatably fixed to upperclutch 428 and upper clutch 428 is rotatably fixed to body portion 474of main shaft 432. Thus, when articulation lever 422 is rotated, upperclutch 428, main shaft 432, and cam member 480 rotate in relation totranslation member 434. Although not shown, translation member 434 isconfined to linear movement within rotatable member 438. As such, whencam member 480 is driven in rotation, translation member 434 is forcedto move linearly within rotatable member 438. Since translation member438 is fastened to articulation link 123 (FIG. 10A), linear movement oftranslation member 438 effects linear movement of articulation link 123to articulate tool assembly 17.

Referring now to FIGS. 65 and 75, biasing member 426 is positionedbetween upper face 469 of base portion 454 of upper clutch 428 and aninner surface 510 of cover 424. Biasing member urges lower face 468(FIG. 68) of upper clutch 428 into engagement with serrated portion 444(FIG. 70) of lower clutch 430 such that spaced projections 470 on upperclutch 428 are received within shallow serrations 448 or deep serrations450 of lower clutch 430. Engagement between projections 470 andserrations 448 and 450 releasably secure articulation mechanism 420 in afixed position to thereby releasably secure a tool assembly 17 (FIG. 1)at a fixed angle of articulation. See FIG. 76.

Referring to FIGS. 77-80, when articulation lever 422 is rotated, (asdiscussed above) upper clutch 428 and main shaft 432 are driven inrotation. When base portion 454 of upper clutch 428 is rotated inrelation to serrated portion 444 of lower clutch 428, the triangularprojections 470 are driven against angled serrations 448 and 450. Whenthis occurs, upper clutch 428 is urged upwardly against the bias ofbiasing member 426 (FIG. 78) to disengage projections 470 fromserrations 448 or 450 (FIG. 79), to allow rotation of upper clutch 428,and thus, main shaft 432. Thereafter, biasing member 426 urges upperclutch downwardly to urge projection 470 back into engagement with thenext serration (FIG. 80). It is noted, projections 470 are positioned tobe received within deep serrations 450 when tool assembly 17 (FIG. 1) isin its non-articulated position aligned with body portion 14 (FIG. 1).This provides increased resistance to movement of tool assembly 17 fromits non-articulated position. Desirably, the deep serrations 450correspond to the non-articulated position of the tool assembly 17.However, deep serrations may be incorporated into the mechanism toprovide other positions with increased resistance to movement.

With reference to FIGS. 68A and 70A, another embodiment of an upperclutch 428′ and a lower clutch 430′, respectively, is illustrated. Inthis embodiment, upper clutch 428′ includes a lower face 468′ which ispositioned in juxtaposed alignment with a serrated portion 444′ of lowerclutch 430′. Lower face 468′ includes two spaced projections 470′configured to be received within serrations 450 a-450 f of lower clutch430′.

As shown, serrations 450 a-450 f are symmetrically disposed in quadrants(i.e., about two axes) about lower clutch 430′. A first axis of symmetryextends between an opposing pair of serrations 450 a-450 a; a secondaxis of symmetry, which is off-set 90° from the first axis of symmetry,extends between an opposing pair of serrations 450 f-450 f As such,there are two of each serrations 450 a and 450 f, and there are four ofeach serrations 450 b-450 e. The orientation of projections 470′ andserrations 450 a-450 f help provide articulation lever 422 with a 90°range of rotation.

With particular regard to FIG. 70A, the spacing and the correspondingangle between some adjacent serrations is substantially equal, and thespacing between other adjacent serrations is non-equal. In particular,the space and corresponding angle between adjacent serrations 450 b, 450c, and 450 d is substantially equal, and the space and correspondingangle between adjacent serrations 450 d, 450 e and 450 f issubstantially equal. The space and angle between adjacent serrations 450a and 450 b is greater than the space and angle between adjacentserrations 450 d and 450 e, which is greater than the spacing and anglesbetween adjacent serrations 450 b and 450 c. More particularly, forexample, an angle α1 between valleys of adjacent serrations 450 a and450 b may be between about 25° and about 35°, and may be equal to about30° ; an angle α2 between valleys of adjacent serrations 450 b and 450c, and 450 c and 450 d may be between about 5° and about 15°, and may beequal to about 10° ; and an angle α3 between valleys of adjacentserrations 450 d and 450 e, and 450 e and 450 f may be between about 15°and about 25°, and may be equal to about 20°. In the illustratedembodiment, lower clutch 430′ includes exactly twenty serrations.

As can be appreciated, the tool assembly 17 has a greater resistance tomovement in articulation as the tool assembly 17 approaches 90 degreesof articulated movement. Drive beam 266 bends as the tool assembly 17 isarticulated, and the greater degree of articulation, the greater forcerequired to bend the drive beam 266 to further articulate the toolassembly 17. The mechanism is more efficient initially. For the closerspaced serrations shown, the tool assembly 17 moves the same distance inarticulation as for the serrations with greater spacing.

With continued reference to FIG. 70A, lower clutch 430′ includes aplurality of tabs 446′ which are dimensioned to receive correspondingslots or grooves (not shown) on the shoulder of receptacle 436. As canbe appreciated, the interaction between tabs 446′ and the correspondingslots help prevent rotation movement of lower clutch 430′ with respectto receptacle 436. It is envisioned that at least one tab isdifferently-sized from at least one other tab to help ensure properangular placement of lower clutch 430′ within receptacle 436.Additionally or alternatively, it is envisioned that adjacent tabs 446′and corresponding slots are spaced at a non-90° angle from one other,which also helps ensure proper angular placement of lower clutch 430′within receptacle 436. Further, tabs 446′ help ensure proper placementof lower clutch 430′ within receptacle 436, and also help ensure thatlower clutch 430′ is not positioned up-side-down within receptacle 436.

Referring to FIGS. 8-10 and 16, a disposable loading unit sensingmechanism extends within stapling apparatus 10 from elongated body 14into handle assembly 12. The sensing mechanism includes a sensor tube176 which is slidably supported within bore 26 of elongated body 14. Thedistal end of sensor tube 176 is positioned towards the distal end ofelongated body 14 and the proximal end of sensor tube 176 is securedwithin the distal end of a sensor cylinder 176 via a pair of nubs 180.The distal end of a sensor link 182 is secured to the proximal end ofsensor cylinder 178. Sensor link 182 (See FIGS. 8 a and 8 c) has abulbous end 184 which engages a camming surface 83 a on pivotablelocking member 83. When a disposable loading unit (not shown) isinserted in the distal end of elongated body 14, the disposable loadingunit engages the distal end 177 of sensor tube 176 to drive sensor tube176 proximally, and thereby drive sensor cylinder 178 and sensor link182 proximally. Movement of sensor link 182 proximally causes bulbousend 184 of sensor link 182 to move distally of camming surface 83 a toallow locking member 83 to pivot under the bias of spring 92 from aposition permitting firing of stapling apparatus 10 to a blockingposition, wherein blocking member 83 is positioned to engage actuationshaft 46 and prevent firing of stapling apparatus 10. Sensor link 182and locking member 83 function to prevent firing of surgical instrument10 after a disposable loading unit has been secured to elongated body14, without first operating firing lockout assembly 80. It is noted thatmovement of link 182 proximally permits locking member 83 to move to itsposition shown in FIG. 5.

Referring again to FIGS. 9-12, cam member 136 includes recess 154. Alocking ring 184 having a nub portion 186 configured to be receivedwithin recess 154 is positioned about sensor cylinder 178 between acontrol tab portion 188 and a proximal flange portion 190. A spring 192positioned between flange portion 190 and locking ring 184 urges lockingring distally about sensor cylinder 178. When an articulating disposableloading unit 16 b having an extended insertion tip 193 is inserted intothe distal end of elongated body 14 of stapling apparatus 10, insertiontip 193 causes tab portion 188 to move proximally into engagement withlocking ring 184 to urge locking ring 184 and nub 186 proximally ofrecess 154 in cam member 136 (See FIG. 12 b). With nub 186 positionedproximally of recess 154, cam member 136 is free to move transversely toeffect articulation of stapling apparatus 10. A non-articulatingdisposable loading unit does not have an extended insertion tip (SeeFIG. 12 a). As such, when a non-articulating disposable loading unit isinserted in elongated body 14, sensor cylinder 178 is not retractedproximally a sufficient distance to move nub 186 from recess 154. Thus,cam member 136 is prevented from moving transversely by nub 186 oflocking ring 184 which is positioned in recess 154 and articulationlever 30 is locked in its central position.

Referring to FIGS. 16-18, the distal end of elongated body 14 includes acontrol rod locking mechanism 190 which is activated during insertion ofa disposable loading unit into elongated body 14. Control rod lockingmechanism 190 includes a blocking plate 192 which is biased distally bya spring 194 and includes a proximal finger 189 having angled camsurface 195. A semi-circular engagement member 196 is biasedtransversely towards control rod 52 by a spring 197. Control rod 52includes an annular recess 199 configured to receive engagement member196. Blocking plate 192 is movable from a distal position spaced fromengagement member 196 to a proximal position located behind engagementmember 196. In the proximal position, engagement member 196 is preventedfrom being biased from recess 199 by engagement with blocking plate 192.During insertion of a disposable loading unit 16 (See FIG. 1) into thedistal end of elongated body 14, as will be described in further detailbelow, cam surface 195 of blocking plate 192 is engaged by a nub 254(FIG. 30) on the disposable loading unit 16 as the disposable loadingunit is rotated into engagement with elongated body 14 to urge plate 192to the proximal position. Engagement member 196, which is positionedwithin recess 199, is retained therein by blocking plate 192 while nub254 engages cam surface 195 to prevent longitudinal movement of controlrod 52 during assembly. When the disposable loading unit 16 is properlypositioned with respect to the elongated body 14, nub 254 on theproximal end of the disposable loading unit 16 passes off cam surface195 allowing spring 194 to return blocking plate 192 to its distalposition to permit subsequent longitudinal movement of control rod 52.It is noted that when the disposable loading unit nub passes off camsurface 195, an audible clicking sound is produced indicating that thedisposable loading unit 16 is properly fastened to the elongated body14.

Referring to FIGS. 19 and 20, disposable loading unit 16 includes aproximal housing portion 200 adapted to releasably engage the distal endof body portion 14 (FIG. 1). A mounting assembly 202 is pivotallysecured to the distal end of housing portion 200, and is configured toreceive the proximal end of tool assembly 17 such that pivotal movementof mounting assembly 202 about an axis perpendicular to the longitudinalaxis of housing portion 200 effects articulation of tool assembly 17.

Referring to FIGS. 21-26, tool assembly 17 preferably includes anvilassembly 20 and cartridge assembly 18. Anvil assembly 20 includes anvilportion 204 having a plurality of staple deforming concavities 206 (FIG.22) and a cover plate 208 secured to a top surface of anvil portion 204to define a cavity 210 (FIG. 24) therebetween. Cover plate 208 isprovided to prevent pinching of tissue during clamping and firing ofstapling apparatus 10. Cavity 210 is dimensioned to receive a distal endof an axial drive assembly 212 (See FIG. 27). A longitudinal slot 214extends through anvil portion 204 to facilitate passage of retentionflange 284 of axial drive assembly 212 into the anvil cavity 210. Acamming surface 209 formed on anvil portion 204 is positioned to engageaxial drive assembly 212 to facilitate clamping of tissue 198. A pair ofpivot members 211 formed on anvil portion 204 are positioned withinslots 213 formed in carrier 216 to guide the anvil portion between theopen and clamped positions. A pair of stabilizing members 215 engage arespective shoulder 217 formed on carrier 216 to prevent anvil portion204 from sliding axially relative to staple cartridge 220 as cammingsurface 209 is deformed.

Cartridge assembly 18 includes a carrier 216 which defines an elongatedsupport channel 218. Elongated support channel 218 is dimensioned andconfigured to receive a staple cartridge 220. Corresponding tabs 222 andslots 224 formed along staple cartridge 220 and elongated supportchannel 218 function to retain staple cartridge 220 within supportchannel 218. A pair of support struts 223 formed on staple cartridge 220are positioned to rest on side walls of carrier 216 to further stabilizestaple cartridge 220 within support channel 218.

Staple cartridge 220 includes retention slots 225 for receiving aplurality of fasteners 226 and pushers 228. A plurality of spaced apartlongitudinal slots 230 extend through staple cartridge 220 toaccommodate upstanding cam wedges 232 of actuation sled 234. A centrallongitudinal slot 282 extends along the length of staple cartridge 220to facilitate passage of a knife blade 280. During operation of surgicalstapler 10, actuation sled 234 translates through longitudinal slots 230of staple cartridge 220 to advance cam wedges 232 into sequentialcontact with pushers 228, to cause pushers 228 to translate verticallywithin slots 224 and urge fasteners 226 from slots 224 into the stapledeforming cavities 206 of anvil assembly 20.

Referring to FIGS. 27 and 28, mounting assembly 202 includes upper andlower mounting portions 236 and 238. Each mounting portion includes athreaded bore 240 on each side thereof dimensioned to receive threadedbolts 242 (See FIG. 21) for securing the proximal end of carrier 216thereto. A pair of centrally located pivot members 244 (See FIG. 21)extends between upper and lower mounting portions via a pair of couplingmembers 246 which engage the distal end of housing portion 200. Couplingmembers 246 each include an interlocking proximal portion 248 configuredto be received in grooves 250 formed in the proximal end of housingportion 200 to retain mounting assembly 202 and housing portion 200 in alongitudinally fixed position in relation thereto.

Housing portion 200 of disposable loading unit 16 includes an upperhousing half 250 and a lower housing half 252 contained within an outercasing 251. The proximal end of housing half 250 includes engagementnubs 254 for releasably engaging elongated body 14 and an insertion tip193. Nubs 254 form a bayonet type coupling with the distal end of body14 which will be discussed in further detail below. Housing halves 250and 252 define a channel 253 for slidably receiving axial drive assembly212. A second articulation link 256 is dimensioned to be slidablypositioned within a slot 258 formed between housing halves 250 and 252.A pair of blow out plates 254 are positioned adjacent the distal end ofhousing portion 200 adjacent the distal end of axial drive assembly 212to prevent outward bulging of drive assembly 212 during articulation oftool assembly 17.

Referring to FIGS. 29-30, second articulation link 256 includes at leastone elongated metallic plate. Preferably, two or more metallic platesare stacked to form link 256. The proximal end of articulation link 256includes a hook portion 258 configured to engage first articulation link123 (See FIG. 9) and the distal end includes a loop 260 dimensioned toengage a projection 262 formed on mounting assembly 202. Projection 262is laterally offset from pivot pin 244 such that linear movement ofsecond articulation link 256 causes mounting assembly 202 to pivot aboutpivot pins 244 to articulate tool assembly 17.

Referring also to FIGS. 31-34, axial drive assembly 212 includes anelongated drive beam 266 including a distal working head 268 and aproximal engagement section 270. Drive beam 266 may be constructed froma single sheet of material or, preferably, multiple stacked sheets.Engagement section 270 includes a pair of engagement fingers 270 a and270 b which are dimensioned and configured to mountingly engage a pairof corresponding retention slots 272 a and 272 b formed in drive member272. Drive member 272 includes a proximal porthole 274 configured toreceive the distal end 276 of control rod 52 (See FIG. 35) when theproximal end of disposable loading unit 16 is engaged with elongatedbody 14 of surgical instrument 10.

The distal end of drive beam 266 is defined by a vertical support strut278 which supports a knife blade 280, and an abutment surface 283 whichengages the central portion of actuation sled 234 during a staplingprocedure. Surface 285 at the base of surface 283 is configured toreceive a support member 287 slidably positioned along the bottom of thestaple cartridge 220. Knife blade 280 is positioned to translateslightly behind actuation sled 234 through a central longitudinal slot282 in staple cartridge 220 (FIG. 30) to form an incision between rowsof stapled body tissue. A retention flange 284 projects distally fromvertical strut 278 and supports a cylindrical cam roller 286 at itsdistal end. Cam roller 286 is dimensioned and configured to engage camsurface 209 on anvil body 204 to clamp anvil portion 204 against bodytissue.

Referring also to FIGS. 36-39, a locking device 288 is pivotally securedto drive member 270 about a pivot pin 290. Locking device 288 includes apair of elongate glides 292 and 294 which define a channel 296. A web298 joins a portion of the upper surfaces of glides 292 and 294, and isconfigured and dimensioned to fit within elongated slot 298 formed indrive beam 266 at a position distal of drive member 270. Horizontal cams300 and 302 extend from glides 292 and 294 respectively, and areaccommodated along an inner surface of lower housing half 252. As bestshown in FIG. 42, a torsion spring 304 is positioned adjacent drivemember 270 and engages horizontal cams 300 and 302 of locking device 288to normally bias locking device 288 downward toward lower housing half252 onto ledge 310. Locking device 288 translates through housingportion 200 with axial drive assembly 212. Operation of locking device288 will be described below.

Sequence of Operation

Referring to FIGS. 40-44, to use stapling instrument 10, a disposableloading unit 16 is first secured to the distal end of elongated body 14.As discussed above, stapling instrument 10 can be used with articulatingand non-articulating disposable loading units having linear rows ofstaples between about 30 mm and about 60 mm. To secure disposableloading unit 16 to elongated body 14, the distal end 276 of control rod52 is inserted into insertion tip 193 of disposable loading unit 16, andinsertion tip 193 is slid longitudinally into the distal end ofelongated body 14 in the direction indicated by arrow “A” in FIG. 41such that hook portion 258 of second articulation link 256 slides withina channel 310 in elongated body 314. Nubs 254 will each be aligned in arespective channel (not shown) in elongated body 14. When hook portion258 engages the proximal wall 312 of channel 310, disposable loadingunit 16 is rotated in the direction indicated by arrow “B” in FIGS.41-44 to move hook portion 258 of second articulation link 256 intoengagement with finger 164 of first articulation link 123. Nubs 254 alsoforms a bayonet type coupling within annular channel 314 in body 14.During rotation of loading unit 16, nubs 254 engage cam surface 195(FIG. 41) of block plate 192 to initially move plate 192 in thedirection indicated by arrow “C” in FIGS. 41 and 43 to lock engagementmember 196 in recess 199 of control rod 52 to prevent longitudinalmovement of control rod 52 during attachment of disposable loading unit16. During the final degree of rotation, nubs 254 disengage from camsurface 195 to allow blocking plate 192 to move in the directionindicated by arrow “D” in FIGS. 42 and 44 from behind engagement member196 to once again permit longitudinal movement of control rod 52.

Referring to FIGS. 43 and 43 a, when insertion tip 193 engages thedistal end of sensor tube 176, the disposable loading unit sensingmechanism is actuated. Insertion tip 193 engages and moves sensor tube176 proximally in the direction indicated by arrow “E” in FIG. 43. Asdiscussed above, proximal movement of sensor tube 176 effects proximalmovement of sensor cylinder 178 and sensor link 182 in the directionindicated by arrow “E” in FIG. 43 a to pivot locking member 83counter-clockwise, as indicated by arrow “Y” in FIG. 43 a, from anon-blocking position to a position blocking movement of actuation shaft46.

Referring to FIGS. 46-49, with a disposable loading unit attached tostapling instrument 10, tool assembly 17 can be positioned about tissue320 (FIG. 45). To clamp tissue between anvil assembly 20 and cartridgeassembly 18, stationary handle 24 is moved in the direction indicated byarrow “E” in FIG. 46 against the bias of torsion spring 40 to movedriving pawl 42 into engagement with shoulder 322 on actuation shaft 46.Engagement between shoulder 322 and driving pawl 42 advances actuationshaft 46 and thus advances control rod 52 distally. Control rod 52 isconnected at its distal end to axial drive assembly 212 (FIG. 48),including drive beam 266, such that distal movement of control rod 52effects distal movement of drive beam 266 in the direction indicated byarrow “F” in FIGS. 48 and 49, moving cam roller 286 into engagement withcam surface 209 on anvil portion 204 to urge anvil portion 204 in thedirection indicated by arrow “G” in FIG. 49. It is noted that onecomplete stroke of movable handle 24 advances actuation shaft 46approximately 15 mm which is sufficient to clamp tissue during the firststroke but not to fire staples.

As discussed above with respect to the anti-reverse clutch mechanism,during the first (clamping) stroke of movable handle 24, slide plate 102(FIG. 46) prevents locking pawl 54 from engaging toothed rack 48. Tomaintain actuation shaft 46 in its longitudinal position after handle 24is released, an engagement member 324 (FIG. 47) is provided on lockingmember 83 to engage shoulder 326 on actuation shaft 46 and retain shaft46 in its longitudinal position (See FIG. 47). Upon release of movablehandle 24, drive pawl 42 moves over rack 48 as torsion spring 40 returnshandle 24 to a position spaced from stationary handle 22. In thisposition, driving pawl 42 is urged into engagement with toothed rack 48to retain actuation shaft 46 in its longitudinal fixed position.

In order to fire staples, movable handle 24 is actuated again, i.e.,moved through another stroke. As discussed above, stapling apparatus 10is capable of receiving disposable loading units having linear rows ofstaples of between about 30 mm and about 60 mm. Since each stroke of themovable handle 24 preferably advances actuation shaft 46 15 mm, and onestroke is required to clamp tissue, the movable handle must be actuated(n+1) strokes to fire staples, where n is the length of the linear rowsof staples in the disposable loading unit attached to staplinginstrument 10 divided by 15 mm.

Referring to FIG. 50, prior to being able to fire staples, firinglockout assembly 80 (FIG. 4) must be actuated to move locking surface 88from its blocking position (FIG. 47) to a non-blocking position. This isaccomplished by pressing down on plunger 82 to move camming surface 85into engagement with sidewalls of slot 89 of locking member 83 to pivotlocking member 83 in the direction indicated by arrow “G” in FIG. 50(see also FIG. 5). Thereafter, movable handle 24 may be actuated anappropriate number of strokes to advance actuation shaft 46, and thuscontrol rod 52 and drive beam 266, distally in the direction indicatedby arrow “H” in FIGS. 51 and 52 to advance actuation sled 234 throughstaple cartridge 220 to effect ejection of staples. It is noted thatafter the first or clamping stroke of movable handle 54 (during thesecond stroke), slide 102 passes over locking pawl 54 allowing torsionspring 56 to move locking pawl 54 in the direction indicated by arrow“I” in FIG. 50 into engagement with toothed rack 48 to retain actuationshaft 46 in its longitudinal position.

Referring to FIG. 53, to retract actuation shaft 46 and thus control rod52 and drive member 266 after firing staples, retraction knobs 32 (seeFIG. 1) are pulled proximally causing pins 66 to move release plate 64in the direction indicated by arrow “J” in FIG. 53 over teeth 48 todisengage drive pawl 42 from engagement with teeth 48. As discussedabove, with respect to the anti-reverse clutch mechanism, locking pawl54 is urged by slide plate 102 out of engagement with toothed rack 48(not shown) to permit actuation shaft 46 to be moved proximally, in thedirection indicated by arrow “L”, after drive pawl 42 is disengaged fromteeth 48.

Referring to FIG. 54, in order to retract actuation shaft 46 prior tofiring stapling apparatus, i.e., when locking pawl is currently engagedwith toothed racked 48, emergency return button 112 is pushed in thedirection indicated by arrow “Z” in FIG. 54 to disengage locking pawl 54from toothed rack 48. Retraction knobs 32 (FIG. 1) must also beconcurrently pulled rearwardly, as discussed above, to release drivepawl 42 from rack 48.

Referring to FIGS. 55-61, when an articulating disposable loading unitis secured to elongated body 14 and articulation lever 30 is pivoted inthe direction indicated by arrow “M” in FIG. 55, cam member 136 is movedtransversely by projection 142 (FIG. 10) in the direction indicated byarrow “N” between flanges 170 and 172 of rotation knob 28. Sincetranslation member 138 is prevented from rotating by ridges 156 (FIG.13), pin 166, which is fixedly secured to translation member 138, isforced to move along stepped cam surface 148. Movement of pin 166 causescorresponding movement of translation member 138 in the directionindicated by arrow “P” in FIGS. 55 and 56 to advance first articulationlink 123 in the distal direction. The distal end of first articulationlink 123 engages the proximal end of second articulation link 256 (FIG.42) which is connected to projection 262 on mounting assembly 202 toadvance second link 256 in the direction indicated by arrow “Q” in FIG.57. Projection 262 is laterally offset from pivot members 244, such thatdistal advancement of second articulation link 256 causes mountingassembly 202 and thus tool assembly 17 to pivot in the directionindicated by arrow “R” in FIGS. 57 and 58. Note in FIG. 59 that rotationmember 28 can be rotated to rotate elongated body 14 about itslongitudinal axis while tool assembly 17 is articulated.

An embodiment of the articulation of tool assembly 17 is illustrated inFIGS. 60-61. In this embodiment, articulation of tool assembly 17 occursin the opposite direction to that described above. When secondarticulation link 256 is retracted by rotating articulation lever 30 ina counter-clockwise direction (not shown) as viewed in FIG. 55, pin 66is forced to move proximally along stepped camming surface 148, movingtranslation member 138 and first articulation link 123 proximally.Movement of first articulation link 123 proximally, causes secondarticulation link 256 to move proximally as indicated by arrow “S” inFIG. 58, to rotate tool assembly 17 in a clockwise direction, asindicated by arrow “T” in FIG. 61. As can be appreciated, surgicalinstrument 10 can be configured such that proximal movement of firstarticulation link 123 causes tool assembly 17 to rotate in acounter-clockwise direction.

Referring to FIG. 12, movement of pin 166 (FIG. 9) between adjacent stepportions 340 causes tool assembly 17 to articulate 22.5 degrees. Cammingsurface 148 includes five step portions 340. The third step portioncorresponds to the non-articulated tool assembly position, whereas thefirst and the fifth step portions correspond to articulation of toolassembly 17 to forty-five degrees. Each step portion is flat to retainarticulation lever 30 in a fixed position when pin 166 is engagedtherewith.

Referring now to FIGS. 37, 39, 62 and 63, the sequence of lockoutoperation will be described in detail. In FIG. 39, lockout device 288 isshown in its prefixed position with horizontal cams 300 and 302 restingon top of projections 330 formed in the sidewalls of lower housing half252 (FIG. 37). In this position, locking device 288 is held up out ofalignment with projection 332 formed in the bottom surface of lowerhousing half 252, and web 298 is in longitudinal juxtaposition withshelf 334 defined in drive beam 266. This configuration permits theanvil 20 (FIG. 38) to be opened and repositioned onto the tissue to bestapled until the surgeon is satisfied with the position withoutactivating locking device 288 to disable the disposable loading unit 16.

As shown in FIG. 62, upon distal movement of drive beam 266, lockingdevice 288 rides off of projections 330 (not shown) and is biased intoengagement with base lower housing half 252 by spring 304, distal toprojection 332. Locking device 288 remains in this configurationthroughout firing of the apparatus.

Upon retraction of the drive beam 266 in the direction indicated byarrow “U” in FIG. 62, locking device 288 passes under projections 330and rides over projection 332 until the distal-most portion of lockingdevice 288 is proximal to projection 332. Spring 304 biases lockingdevice 288 into juxtaposed alignment with projection 332, effectivelydisabling the disposable loading unit. If an attempt is made toreactuate the apparatus, the control rod 52 will abut a proximal endsurface of locking device 288 which surface is diagonally sloped toimpart a moment about pivot pin 342 such that the distal end of lockingdevice 288 is rotationally urged into contact with projection 332.Continued distal force in the direction indicated by arrow “W” in FIG.63, will only serve to increase the moment applied to the locking devicethus the locking device will abut projection 332 and inhibit distalmovement of the control rod 52.

Referring again to FIGS. 41-44, the disabled or locked disposableloading unit can be removed from the distal end of elongated body 14 byrotating disposable loading unit 16 in the direction opposite to thedirection indicated by arrow “B” in FIGS. 41, 42 and 44, to disengagehook portion 258 of second articulation link 256 from finger 164 offirst articulation link 123, and to disengage nubs 254 from withinchannel 314 of elongated body 14. After rotation, disposable loadingunit 16 can be slid in the direction opposite to that indicated by arrow“A” in FIG. 41 to detach body 14 from disposable loading unit 16.Subsequently, additional articulating and/or non-articulating disposableloading units can be secured to the distal end of elongated body, asdescribed above, to perform additional surgical stapling and/or cuttingprocedures. As discussed above, each disposable loading unit may includelinear rows of staples which vary from about 30 mm to about 60 mm.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, the stapling apparatus neednot apply staples but rather may apply two part fasteners as is known inthe art. Further, the length of the linear row of staples or fastenersmay be modified to meet the requirements of a particular surgicalprocedure. Thus, the length of a single stroke of the actuation shaftand/or the length of the linear row of staples and/or fasteners within adisposable loading unit may be varied accordingly. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended thereto.

1-21. (canceled)
 22. A surgical instrument comprising: an articulationmechanism including an upper portion and a lower portion, the lowerportion including a plurality of serrations and being positioned injuxtaposed relation with the upper portion, the upper portion includingat least one projection positioned to engage the serrations of the lowerportion; wherein an angle between a first pair of adjacent serrations isdefined as a first angle, an angle between a second pair of adjacentserrations is defined as a second angle, and an angle between a thirdpair of adjacent serrations is defined as a third angle, and whereineach of the first angle, the second angle, and the third angle aredifferent from one another.
 23. The surgical instrument according toclaim 22, wherein the first angle is between about 25° and about 35°.24. The surgical instrument according to claim 22, wherein the secondangle is between about 5° and about 15°.
 25. The surgical instrumentaccording to claim 22, wherein the third angle is between about 15° andabout 25°.
 26. The surgical instrument according to claim 22, whereinthe first angle is disposed between a first serration and an adjacentsecond serration and is between about 25° and about 35°, and wherein thesecond angle is disposed between the second serration and an adjacentthird serration and is between about 5° and about 15°.
 27. The surgicalinstrument according to claim 26, wherein the second angle is alsodisposed between the third serration and an adjacent fourth serration.28. The surgical instrument according to claim 27, wherein the thirdangle is disposed between the fourth serration and an adjacent fifthserration and is between about 15° and about 25°.
 29. The surgicalinstrument according to claim 22, wherein the serrations aresymmetrically disposed about two axes of the lower portion.
 30. Thesurgical instrument according to claim 22, wherein the upper portionincludes exactly two projections.
 31. An articulation mechanism foraffecting movement of a tool assembly of a surgical instrument between anon-articulated position and at least one articulated position, thearticulation mechanism comprising: a lower portion including a pluralityof serrations; and an upper portion disposed in juxtaposed relation withthe lower portion, the upper portion including at least one projectionpositioned to engage the serrations of the lower portion; wherein anangle between a first pair of adjacent serrations is defined as a firstangle, an angle between a second pair of adjacent serrations is definedas a second angle, and an angle between a third pair of adjacentserrations is defined as a third angle, and wherein each of the firstangle, the second angle, and the third angle are different from oneanother.
 32. The articulation mechanism according to claim 31, whereinthe first angle is between about 25° and about 35°.
 33. The articulationmechanism according to claim 32, wherein the second angle is betweenabout 5° and about 15°.
 34. The articulation mechanism according toclaim 33, wherein the third angle is between about 15° and about 25°.35. The articulation mechanism according to claim 31, wherein the firstangle is disposed between a first serration and an adjacent secondserration and is between about 25° and about 35°, and wherein the secondangle is disposed between the second serration and an adjacent thirdserration and is between about 5° and about 15°.
 36. The articulationmechanism according to claim 35, wherein a fourth serration is disposedadjacent the third serration, and wherein the third angle is disposedbetween the fourth serration and an adjacent fifth serration and isbetween about 15° and about 25°.